Neuromuscular stimulation (the electrical excitation of nerves and/or muscle to directly elicit the contraction of muscles) and neuromodulation stimulation (the electrical excitation of nerves, often afferent nerves, to indirectly affect the stability or performance of a physiological system) and brain stimulation (the stimulation of cerebral or other central nervous system tissue) can provide functional and/or therapeutic outcomes. While existing systems and methods can provide remarkable benefits to individuals requiring neuromuscular or neuromodulation stimulation, many limitations and issues still remain. For example, existing systems often can perform only a single, dedicated stimulation function.
Today there are a wide variety of implantable medical devices that can be used to provide beneficial results in diverse therapeutic and functional restorations indications. For example, implantable pulse generators can provide therapeutic and functional restoration outcomes in the field of urology, such as for the treatment of (i) urinary and fecal incontinence; (ii) micturition/retention; (iii) restoration of sexual function; (iv) defecation/constipation; (v) pelvic floor muscle activity; and/or (vi) pelvic pain. Implantable pulse generators can also be used for deep brain stimulation, compensation for various cardiac dysfunctions, pain management by interfering with or blocking pain signals, vagal nerve stimulation for control of epilepsy, depression, or other mood/psychiatric disorders, the treatment of obstructive sleep apnea, for gastric stimulation to prevent reflux or to reduce appetite or food consumption, and can be used in functional restorations indications such as the restoration of motor control.
There exists both external and implantable devices for providing beneficial results in diverse therapeutic and functional restorations indications. The operation of these devices typically includes the use of an electrode placed either on the external surface of the skin, a vaginal or anal electrode, or a surgically implanted electrode. Although these modalities have shown the ability to provide a neurological stimulation with positive effects, they have received limited acceptance by patients because of their limitations of portability, limitations of treatment regimes, and limitations of ease of use and user control.
Implantable devices have provided an improvement in the portability of neurological stimulation devices, but there remains the need for continued improvement. Implantable stimulators described in the art have additional limitations in that they are challenging to surgically implant because they are relatively large, they require direct skin contact for programming and for turning on and off, and only provide a single dedicated stimulation function. In addition, current implantable stimulators are expensive, owing in part to their limited scope of usage.
These implantable devices are also limited in their ability to provide sufficient power which limits their use in a wide range of stimulation applications, requires surgical replacement of the device when the batteries fail, and limits their acceptance by patients. Rechargeable batteries have been used but are limited by the need to recharge a power supply frequently (e.g., daily), and the inconvenience of special recharge methods.
More recently, small, implantable microstimulators have been introduced that can be injected into soft tissues through a cannula or needle. Although these small implantable stimulation devices have a reduced physical size, their application to a wide range of simulation applications is limited. Their micro size extremely limits their ability to maintain adequate stimulation strength for an extended period without the need for frequent recharging of their internal power supply (battery). Additionally, their very small size limits the tissue volumes through which stimulus currents can flow at a charge density adequate to elicit neural excitation. This, in turn, limits or excludes many applications.
For each of these examples, the medical device (i.e., an implantable pulse generator), is often controlled using microprocessors with resident operating system software (code). This operating system software may be further broken down into subgroups including system software and application software. The system software controls the operation of the medical device while the application software interacts with the system software to instruct the system software on what actions to take to control the medical device based upon the actual application of the medical device (i.e., to control incontinence or the restoration of a specific motor control).
As the diverse therapeutic and functional uses of implantable medical devices increases, and become more complex, system software having a versatile interface is needed to play an increasingly important role. This interface allows the system software to remain generally consistent based upon the particular medical device, and allows the application software to vary greatly depending upon the particular application. As long as the application software is written so it can interact with the interface, and in turn the system software, the particular medical device can be used in a wide variety of applications with only changes to application specific software. This allows a platform device to be manufactured in large, more cost effective quantities, with application specific customization occurring at a later time.
It is time that systems and methods for providing neurological stimulation address not only specific prosthetic or therapeutic objections, but also address the quality of life of the individual requiring the beneficial stimulation. In addition, there remains the need for improved size, operation, and power considerations of implantable medical devices that will improve the quality of life issues for the user.